Abstract

Reversible watermarking is a process which is used to authenticate the multimedia content. It checks the integrity of the digital data in order to recover the original data without any distortion. Industries like as medical services, military organization and legal services which are dealing the sensitive data where the minimal alteration is difficult to be tolerated is the application domain of Reversible watermarking. In this thesis, we have proposed a Tamper localization approach for histogram bin shifting based Reversible watermarking algorithm,where original image can be obtained from the watermarked image without any distortion. Tamper localization approach finds out the tampered region of the image, which is used for the selective rejection of the cover image. General application of reversible watermarking procedure says that the entire image gets rejected at receiver side due to the hash mismatch and authentication failure. By using our approach when the hash mismatch occurs the selected part of the image is rejected. This will reduce the re-transmission overhead on the communication channel and limited bandwidth is required due to small sub-part of re-transmission of the image. Here we are taking the advantage of the multiple minimum and maximum points of the histogram for embedding purpose. This will increase the embedding capacity. We have embedded the hash into smaller sub-part of the image until embedding is possible. The hash is generated through the some known cryptographic hash function such as SHA or MD5. This will help us to find out the tampered region at the receiver end while extracting the hash, in the case of hash mismatch occur in cover image which will lead to selective rejection of the cover images.